ajax 基础实例

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优点：使用ajax读取数据文件，不需要刷新页面就能取出文件数据<br><br><br><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <title></title>

<script type="text/javascript">

    function
ajax(url, fnSucc, fnFaild) {

        //1.创建Ajax对象

        if
(window.XMLHttpRequest) {

            var
oAjax = new
XMLHttpRequest();

        }

        else
{

            var
oAjax = new
ActiveXObject("Microsoft.XMLHTTP");

        }

        //2.连接服务器

        //open(方法, 文件名, 异步传输)

        oAjax.open(‘GET‘, url, true);

        //3.发送请求

        oAjax.send();

        //4.接收返回

        oAjax.onreadystatechange = function
() {

            //oAjax.readyState  //浏览器和服务器，进行到哪一步了

            if
(oAjax.readyState == 4)  //读取完成

            {

                if
(oAjax.status == 200)    //成功

                {

                    fnSucc(oAjax.responseText);

                }

                else
{

                    if
(fnFaild) {

                        fnFaild(oAjax.status);

                    }

                    //alert(‘失败:‘+oAjax.status);

                }

            }

        };

    }

    window.onload = function
() {

        var
oBtn = document.getElementById(‘myDiv‘);

        oBtn.onclick = function
() {

            ajax(‘test1.txt?t=‘+new
Date().getTime(), function
(str) { <br>      //?t=‘+new Date().getTime()  可以控制缓存，即每次改变 test1.txt文件不需要刷新页面既可读取文件改变后的值

1

var
oTxt = document.getElementById(‘txt‘);<br>  oTxt.value = str; }); }; }; <br></script> <br></head> <br><body><br> <input type="button"
id="myDiv"
value="读取"/><br /> <br>用户名: <input type="text"
id="txt"
/><br> <input type="text"
id="Text1"
/> <br></body><br> </html>